2004-05-29 Gonzalo Paniagua Javier <gonzalo@ximian.com>

[mono.git] / mcs / mcs / decl.cs

//
// decl.cs: Declaration base class for structs, classes, enums and interfaces.
//
// Author: Miguel de Icaza (miguel@gnu.org)
//
// Licensed under the terms of the GNU GPL
//
// (C) 2001 Ximian, Inc (http://www.ximian.com)
//
// TODO: Move the method verification stuff from the class.cs and interface.cs here
//

using System;
using System.Collections;
using System.Globalization;
using System.Reflection.Emit;
using System.Reflection;

namespace Mono.CSharp {

        /// <summary>
        ///   Base representation for members.  This is used to keep track
        ///   of Name, Location and Modifier flags, and handling Attributes.
        /// </summary>
        public abstract class MemberCore : Attributable {
                /// <summary>
                ///   Public name
                /// </summary>
                public string Name;

                /// <summary>
                ///   Modifier flags that the user specified in the source code
                /// </summary>
                public int ModFlags;

                /// <summary>
                ///   Location where this declaration happens
                /// </summary>
                public readonly Location Location;

                [Flags]
                public enum Flags {
                        Obsolete_Undetected = 1,                // Obsolete attribute has not been detected yet
                        Obsolete = 1 << 1,                      // Type has obsolete attribute
                        ClsCompliance_Undetected = 1 << 2,      // CLS Compliance has not been detected yet
                        ClsCompliant = 1 << 3,                  // Type is CLS Compliant
                        CloseTypeCreated = 1 << 4,              // Tracks whether we have Closed the type
                        HasCompliantAttribute_Undetected = 1 << 5,      // Presence of CLSCompliantAttribute has not been detected
                        HasClsCompliantAttribute = 1 << 6,                      // Type has CLSCompliantAttribute
                        ClsCompliantAttributeTrue = 1 << 7,                     // Type has CLSCompliant (true)
                }

                /// <summary>
                ///   MemberCore flags at first detected then cached
                /// </summary>
                protected Flags caching_flags;

                public MemberCore (string name, Attributes attrs, Location loc)
                        : base (attrs)
                {
                        Name = name;
                        Location = loc;
                        caching_flags = Flags.Obsolete_Undetected | Flags.ClsCompliance_Undetected | Flags.HasCompliantAttribute_Undetected;
                }

                public abstract bool Define (TypeContainer parent);

                // 
                // Returns full member name for error message
                //
                public virtual string GetSignatureForError ()
                {
                        return Name;
                }

                /// <summary>
                /// Base Emit method. This is also entry point for CLS-Compliant verification.
                /// </summary>
                public virtual void Emit (TypeContainer container)
                {
                        if (!RootContext.VerifyClsCompliance)
                                return;

                        VerifyClsCompliance (container);
                }

                // 
                // Whehter is it ok to use an unsafe pointer in this type container
                //
                public bool UnsafeOK (DeclSpace parent)
                {
                        //
                        // First check if this MemberCore modifier flags has unsafe set
                        //
                        if ((ModFlags & Modifiers.UNSAFE) != 0)
                                return true;

                        if (parent.UnsafeContext)
                                return true;

                        Expression.UnsafeError (Location);
                        return false;
                }

                /// <summary>
                /// Returns instance of ObsoleteAttribute for this MemberCore
                /// </summary>
                public ObsoleteAttribute GetObsoleteAttribute (DeclSpace ds)
                {
                        // ((flags & (Flags.Obsolete_Undetected | Flags.Obsolete)) == 0) is slower, but why ?
                        if ((caching_flags & Flags.Obsolete_Undetected) == 0 && (caching_flags & Flags.Obsolete) == 0) {
                                return null;
                        }

                        caching_flags &= ~Flags.Obsolete_Undetected;

                        if (OptAttributes == null)
                                return null;

                        // TODO: remove this allocation
                        EmitContext ec = new EmitContext (ds.Parent, ds, ds.Location,
                                null, null, ds.ModFlags, false);

                        Attribute obsolete_attr = OptAttributes.Search (TypeManager.obsolete_attribute_type, ec);
                        if (obsolete_attr == null)
                                return null;

                        ObsoleteAttribute obsolete = obsolete_attr.GetObsoleteAttribute (ds);
                        if (obsolete == null)
                                return null;

                        caching_flags |= Flags.Obsolete;
                        return obsolete;
                }

                /// <summary>
                /// Analyze whether CLS-Compliant verification must be execute for this MemberCore.
                /// </summary>
                public override bool IsClsCompliaceRequired (DeclSpace container)
                {
                        if ((caching_flags & Flags.ClsCompliance_Undetected) == 0)
                                return (caching_flags & Flags.ClsCompliant) != 0;

                        if (GetClsCompliantAttributeValue (container) && IsExposedFromAssembly (container)) {
                                caching_flags &= ~Flags.ClsCompliance_Undetected;
                                caching_flags |= Flags.ClsCompliant;
                                return true;
                        }

                        caching_flags &= ~Flags.ClsCompliance_Undetected;
                        return false;
                }

                /// <summary>
                /// Returns true when MemberCore is exposed from assembly.
                /// </summary>
                protected bool IsExposedFromAssembly (DeclSpace ds)
                {
                        if ((ModFlags & (Modifiers.PUBLIC | Modifiers.PROTECTED)) == 0)
                                return false;
                        
                        DeclSpace parentContainer = ds;
                        while (parentContainer != null && parentContainer.ModFlags != 0) {
                                if ((parentContainer.ModFlags & (Modifiers.PUBLIC | Modifiers.PROTECTED)) == 0)
                                        return false;
                                parentContainer = parentContainer.Parent;
                        }
                        return true;
                }

                /// <summary>
                /// Resolve CLSCompliantAttribute value or gets cached value.
                /// </summary>
                bool GetClsCompliantAttributeValue (DeclSpace ds)
                {
                        if (OptAttributes != null) {
                                EmitContext ec = new EmitContext (ds.Parent, ds, ds.Location,
                                                                  null, null, ds.ModFlags, false);
                                Attribute cls_attribute = OptAttributes.GetClsCompliantAttribute (ec);
                                if (cls_attribute != null) {
                                        caching_flags |= Flags.HasClsCompliantAttribute;
                                        return cls_attribute.GetClsCompliantAttributeValue (ds);
                                }
                        }
                        return ds.GetClsCompliantAttributeValue ();
                }

                /// <summary>
                /// Returns true if MemberCore is explicitly marked with CLSCompliantAttribute
                /// </summary>
                protected bool HasClsCompliantAttribute {
                        get {
                                return (caching_flags & Flags.HasClsCompliantAttribute) != 0;
                        }
                }

                /// <summary>
                /// This method is used to testing error 3005 (Method or parameter name collision).
                /// </summary>
                protected abstract bool IsIdentifierClsCompliant (DeclSpace ds);

                /// <summary>
                /// Common helper method for identifier and parameters CLS-Compliant testing.
                /// When return false error 3005 is reported. True means no violation.
                /// And error 3006 tests are peformed here because of speed.
                /// </summary>
                protected bool IsIdentifierAndParamClsCompliant (DeclSpace ds, string name, MemberInfo methodBuilder, Type[] paramTypes)
                {
                        MemberList ml = ds.FindMembers (MemberTypes.Event | MemberTypes.Field | MemberTypes.Method | MemberTypes.Property, 
                                BindingFlags.Public | BindingFlags.Static | BindingFlags.Instance, System.Type.FilterNameIgnoreCase, name);
                
                        if (ml.Count < 2)
                                return true;

                        bool error3006 = false;
                        for (int i = 0; i < ml.Count; ++i) {
                                MemberInfo mi = ml [i];
                                if (name == mi.Name) {
                                        MethodBase method = mi as MethodBase;
                                        if (method == null || method == methodBuilder || paramTypes == null || paramTypes.Length == 0)
                                                continue;

                                        if (AttributeTester.AreOverloadedMethodParamsClsCompliant (paramTypes, TypeManager.GetArgumentTypes (method))) {
                                                error3006 = false;
                                                continue;
                                        }

                                        error3006 = true;
                                }

                                // We need to test if member is not marked as CLSCompliant (false) and if type is not only internal
                                // because BindingFlags.Public returns internal types too
                                DeclSpace temp_ds = TypeManager.LookupDeclSpace (mi.DeclaringType);

                                // Type is external, we can get attribute directly
                                if (temp_ds == null) {
                                        object[] cls_attribute = mi.GetCustomAttributes (TypeManager.cls_compliant_attribute_type, false);
                                        if (cls_attribute.Length == 1 && (!((CLSCompliantAttribute)cls_attribute[0]).IsCompliant))
                                                continue;
                                } else {
                                        string tmp_name = String.Concat (temp_ds.Name, '.', mi.Name);

                                        MemberCore mc = temp_ds.GetDefinition (tmp_name) as MemberCore;
                                        if (!mc.IsClsCompliaceRequired (ds))
                                                continue;
                                }

                                for (int ii = 0; ii < ml.Count; ++ii) {
                                        mi = ml [ii];
                                        if (name == mi.Name)
                                                continue;
                                        Report.SymbolRelatedToPreviousError (mi);
                                }

                                if (error3006)
                                        Report.Error_T (3006, Location, GetSignatureForError ());

                                return error3006;

                        }
                        return true;
                }

                /// <summary>
                /// The main virtual method for CLS-Compliant verifications.
                /// The method returns true if member is CLS-Compliant and false if member is not
                /// CLS-Compliant which means that CLS-Compliant tests are not necessary. A descendants override it
                /// and add their extra verifications.
                /// </summary>
                protected virtual bool VerifyClsCompliance (DeclSpace ds)
                {
                        if (!IsClsCompliaceRequired (ds)) {
                                if (HasClsCompliantAttribute && !IsExposedFromAssembly (ds)) {
                                        Report.Warning_T (3019, Location, GetSignatureForError ());
                                }
                                return false;
                        }

                        if (!CodeGen.Assembly.IsClsCompliant) {
                                if (HasClsCompliantAttribute) {
                                        Report.Error_T (3014, Location, GetSignatureForError ());
                                }
                        }

                        int index = Name.LastIndexOf ('.');
                        if (Name [index > 0 ? index + 1 : 0] == '_') {
                                Report.Error_T (3008, Location, GetSignatureForError () );
                        }

                        if (!IsIdentifierClsCompliant (ds)) {
                                Report.Error_T (3005, Location, GetSignatureForError ());
                        }

                        return true;
                }

        }

        /// <summary>
        ///   Base class for structs, classes, enumerations and interfaces.  
        /// </summary>
        /// <remarks>
        ///   They all create new declaration spaces.  This
        ///   provides the common foundation for managing those name
        ///   spaces.
        /// </remarks>
        public abstract class DeclSpace : MemberCore {
                /// <summary>
                ///   this points to the actual definition that is being
                ///   created with System.Reflection.Emit
                /// </summary>
                public TypeBuilder TypeBuilder;

                //
                // This is the namespace in which this typecontainer
                // was declared.  We use this to resolve names.
                //
                public NamespaceEntry NamespaceEntry;

                public Hashtable Cache = new Hashtable ();
                
                public string Basename;
                
                /// <summary>
                ///   defined_names is used for toplevel objects
                /// </summary>
                protected Hashtable defined_names;

                TypeContainer parent;           

                static string[] attribute_targets = new string [] { "type" };

                public DeclSpace (NamespaceEntry ns, TypeContainer parent, string name, Attributes attrs, Location l)
                        : base (name, attrs, l)
                {
                        NamespaceEntry = ns;
                        Basename = name.Substring (1 + name.LastIndexOf ('.'));
                        defined_names = new Hashtable ();
                        this.parent = parent;
                }

                public void RecordDecl ()
                {
                        if ((NamespaceEntry != null) && (parent == RootContext.Tree.Types))
                                NamespaceEntry.DefineName (Basename, this);
                }

                /// <summary>
                ///   The result value from adding an declaration into
                ///   a struct or a class
                /// </summary>
                public enum AdditionResult {
                        /// <summary>
                        /// The declaration has been successfully
                        /// added to the declation space.
                        /// </summary>
                        Success,

                        /// <summary>
                        ///   The symbol has already been defined.
                        /// </summary>
                        NameExists,

                        /// <summary>
                        ///   Returned if the declation being added to the
                        ///   name space clashes with its container name.
                        ///
                        ///   The only exceptions for this are constructors
                        ///   and static constructors
                        /// </summary>
                        EnclosingClash,

                        /// <summary>
                        ///   Returned if a constructor was created (because syntactically
                        ///   it looked like a constructor) but was not (because the name
                        ///   of the method is not the same as the container class
                        /// </summary>
                        NotAConstructor,

                        /// <summary>
                        ///   This is only used by static constructors to emit the
                        ///   error 111, but this error for other things really
                        ///   happens at another level for other functions.
                        /// </summary>
                        MethodExists,

                        /// <summary>
                        ///   Some other error.
                        /// </summary>
                        Error
                }

                /// <summary>
                ///   Returns a status code based purely on the name
                ///   of the member being added
                /// </summary>
                protected AdditionResult IsValid (string basename, string name)
                {
                        if (basename == Basename)
                                return AdditionResult.EnclosingClash;

                        if (defined_names.Contains (name))
                                return AdditionResult.NameExists;

                        return AdditionResult.Success;
                }

                public static int length;
                public static int small;
                
                /// <summary>
                ///   Introduce @name into this declaration space and
                ///   associates it with the object @o.  Note that for
                ///   methods this will just point to the first method. o
                /// </summary>
                public void DefineName (string name, object o)
                {
                        defined_names.Add (name, o);

#if DEBUGME
                        int p = name.LastIndexOf ('.');
                        int l = name.Length;
                        length += l;
                        small += l -p;
#endif
                }

                /// <summary>
                ///   Returns the object associated with a given name in the declaration
                ///   space.  This is the inverse operation of `DefineName'
                /// </summary>
                public object GetDefinition (string name)
                {
                        return defined_names [name];
                }
                
                bool in_transit = false;
                
                /// <summary>
                ///   This function is used to catch recursive definitions
                ///   in declarations.
                /// </summary>
                public bool InTransit {
                        get {
                                return in_transit;
                        }

                        set {
                                in_transit = value;
                        }
                }

                public TypeContainer Parent {
                        get {
                                return parent;
                        }
                }

                /// <summary>
                ///   Looks up the alias for the name
                /// </summary>
                public string LookupAlias (string name)
                {
                        if (NamespaceEntry != null)
                                return NamespaceEntry.LookupAlias (name);
                        else
                                return null;
                }
                
                // 
                // root_types contains all the types.  All TopLevel types
                // hence have a parent that points to `root_types', that is
                // why there is a non-obvious test down here.
                //
                public bool IsTopLevel {
                        get {
                                if (parent != null){
                                        if (parent.parent == null)
                                                return true;
                                }
                                return false;
                        }
                }

                public virtual void CloseType ()
                {
                        if ((caching_flags & Flags.CloseTypeCreated) == 0){
                                try {
                                        TypeBuilder.CreateType ();
                                } catch {
                                        //
                                        // The try/catch is needed because
                                        // nested enumerations fail to load when they
                                        // are defined.
                                        //
                                        // Even if this is the right order (enumerations
                                        // declared after types).
                                        //
                                        // Note that this still creates the type and
                                        // it is possible to save it
                                }
                                caching_flags |= Flags.CloseTypeCreated;
                        }
                }

                /// <remarks>
                ///  Should be overriten by the appropriate declaration space
                /// </remarks>
                public abstract TypeBuilder DefineType ();
                
                /// <summary>
                ///   Define all members, but don't apply any attributes or do anything which may
                ///   access not-yet-defined classes.  This method also creates the MemberCache.
                /// </summary>
                public abstract bool DefineMembers (TypeContainer parent);

                //
                // Whether this is an `unsafe context'
                //
                public bool UnsafeContext {
                        get {
                                if ((ModFlags & Modifiers.UNSAFE) != 0)
                                        return true;
                                if (parent != null)
                                        return parent.UnsafeContext;
                                return false;
                        }
                }

                public static string MakeFQN (string nsn, string name)
                {
                        if (nsn == "")
                                return name;
                        return String.Concat (nsn, ".", name);
                }

                EmitContext type_resolve_ec;
                EmitContext GetTypeResolveEmitContext (TypeContainer parent, Location loc)
                {
                        type_resolve_ec = new EmitContext (parent, this, loc, null, null, ModFlags, false);
                        type_resolve_ec.ResolvingTypeTree = true;

                        return type_resolve_ec;
                }

                // <summary>
                //    Looks up the type, as parsed into the expression `e' 
                // </summary>
                public Type ResolveType (Expression e, bool silent, Location loc)
                {
                        if (type_resolve_ec == null)
                                type_resolve_ec = GetTypeResolveEmitContext (parent, loc);
                        type_resolve_ec.loc = loc;
                        type_resolve_ec.ContainerType = TypeBuilder;

                        int errors = Report.Errors;
                        TypeExpr d = e.ResolveAsTypeTerminal (type_resolve_ec);
                        
                        if (d == null || d.eclass != ExprClass.Type){
                                if (!silent && errors == Report.Errors){
                                        Report.Error (246, loc, "Cannot find type `"+ e.ToString () +"'");
                                }
                                return null;
                        }

                        if (!d.CheckAccessLevel (this)) {
                                Report.Error_T (122, loc, d.Name);
                                return null;
                        }

                        return d.Type;
                }

                // <summary>
                //    Resolves the expression `e' for a type, and will recursively define
                //    types. 
                // </summary>
                public TypeExpr ResolveTypeExpr (Expression e, bool silent, Location loc)
                {
                        if (type_resolve_ec == null)
                                type_resolve_ec = GetTypeResolveEmitContext (parent, loc);
                        type_resolve_ec.loc = loc;
                        type_resolve_ec.ContainerType = TypeBuilder;

                        TypeExpr d = e.ResolveAsTypeTerminal (type_resolve_ec);
                         
                        if (d == null || d.eclass != ExprClass.Type){
                                if (!silent){
                                        Report.Error (246, loc, "Cannot find type `"+ e +"'");
                                }
                                return null;
                        }

                        return d;
                }
                
                public bool CheckAccessLevel (Type check_type) 
                {
                        if (check_type == TypeBuilder)
                                return true;
                        
                        TypeAttributes check_attr = check_type.Attributes & TypeAttributes.VisibilityMask;
                        
                        //
                        // Broken Microsoft runtime, return public for arrays, no matter what 
                        // the accessibility is for their underlying class, and they return 
                        // NonPublic visibility for pointers
                        //
                        if (check_type.IsArray || check_type.IsPointer)
                                return CheckAccessLevel (TypeManager.GetElementType (check_type));

                        switch (check_attr){
                        case TypeAttributes.Public:
                                return true;

                        case TypeAttributes.NotPublic:

                                // In same cases is null.
                                if (TypeBuilder == null)
                                        return true;

                                //
                                // This test should probably use the declaringtype.
                                //
                                return check_type.Assembly == TypeBuilder.Assembly;
                                
                        case TypeAttributes.NestedPublic:
                                return true;

                        case TypeAttributes.NestedPrivate:
                                string check_type_name = check_type.FullName;
                                string type_name = TypeBuilder.FullName;
                                
                                int cio = check_type_name.LastIndexOf ('+');
                                string container = check_type_name.Substring (0, cio);

                                //
                                // Check if the check_type is a nested class of the current type
                                //
                                if (check_type_name.StartsWith (type_name + "+")){
                                        return true;
                                }
                                
                                if (type_name.StartsWith (container)){
                                        return true;
                                }

                                return false;

                        case TypeAttributes.NestedFamily:
                                //
                                // Only accessible to methods in current type or any subtypes
                                //
                                return FamilyAccessible (check_type);

                        case TypeAttributes.NestedFamANDAssem:
                                return (check_type.Assembly == TypeBuilder.Assembly) &&
                                        FamilyAccessible (check_type);

                        case TypeAttributes.NestedFamORAssem:
                                return (check_type.Assembly == TypeBuilder.Assembly) ||
                                        FamilyAccessible (check_type);

                        case TypeAttributes.NestedAssembly:
                                return check_type.Assembly == TypeBuilder.Assembly;
                        }

                        Console.WriteLine ("HERE: " + check_attr);
                        return false;

                }

                protected bool FamilyAccessible (Type check_type)
                {
                        Type declaring = check_type.DeclaringType;
                        if (TypeBuilder.IsSubclassOf (declaring))
                                return true;

                        string check_type_name = check_type.FullName;
                        
                        int cio = check_type_name.LastIndexOf ('+');
                        string container = check_type_name.Substring (0, cio);
                        
                        //
                        // Check if the check_type is a nested class of the current type
                        //
                        if (check_type_name.StartsWith (container + "+"))
                                return true;

                        return false;
                }

                // Access level of a type.
                const int X = 1;
                enum AccessLevel { // Each column represents `is this scope larger or equal to Blah scope'
                                            // Public    Assembly   Protected
                        Protected           = (0 << 0) | (0 << 1) | (X << 2),
                        Public              = (X << 0) | (X << 1) | (X << 2),
                        Private             = (0 << 0) | (0 << 1) | (0 << 2),
                        Internal            = (0 << 0) | (X << 1) | (0 << 2),
                        ProtectedOrInternal = (0 << 0) | (X << 1) | (X << 2),
                }
                
                static AccessLevel GetAccessLevelFromModifiers (int flags)
                {
                        if ((flags & Modifiers.INTERNAL) != 0) {
                                
                                if ((flags & Modifiers.PROTECTED) != 0)
                                        return AccessLevel.ProtectedOrInternal;
                                else
                                        return AccessLevel.Internal;
                                
                        } else if ((flags & Modifiers.PROTECTED) != 0)
                                return AccessLevel.Protected;
                        
                        else if ((flags & Modifiers.PRIVATE) != 0)
                                return AccessLevel.Private;
                        
                        else
                                return AccessLevel.Public;
                }

                // What is the effective access level of this?
                // TODO: Cache this?
                AccessLevel EffectiveAccessLevel {
                        get {
                                AccessLevel myAccess = GetAccessLevelFromModifiers (ModFlags);
                                if (!IsTopLevel && (Parent != null))
                                        return myAccess & Parent.EffectiveAccessLevel;
                                else
                                        return myAccess;
                        }
                }

                // Return the access level for type `t'
                static AccessLevel TypeEffectiveAccessLevel (Type t)
                {
                        if (t.IsPublic)
                                return AccessLevel.Public;              
                        if (t.IsNestedPrivate)
                                return AccessLevel.Private;
                        if (t.IsNotPublic)
                                return AccessLevel.Internal;
                        
                        // By now, it must be nested
                        AccessLevel parentLevel = TypeEffectiveAccessLevel (t.DeclaringType);
                        
                        if (t.IsNestedPublic)
                                return parentLevel;
                        if (t.IsNestedAssembly)
                                return parentLevel & AccessLevel.Internal;
                        if (t.IsNestedFamily)
                                return parentLevel & AccessLevel.Protected;
                        if (t.IsNestedFamORAssem)
                                return parentLevel & AccessLevel.ProtectedOrInternal;
                        if (t.IsNestedFamANDAssem)
                                throw new NotImplementedException ("NestedFamANDAssem not implemented, cant make this kind of type from c# anyways");
                        
                        // nested private is taken care of
                        
                        throw new Exception ("I give up, what are you?");
                }

                //
                // This answers `is the type P, as accessible as a member M which has the
                // accessability @flags which is declared as a nested member of the type T, this declspace'
                //
                public bool AsAccessible (Type p, int flags)
                {
                        //
                        // 1) if M is private, its accessability is the same as this declspace.
                        // we already know that P is accessible to T before this method, so we
                        // may return true.
                        //
                        
                        if ((flags & Modifiers.PRIVATE) != 0)
                                return true;
                        
                        while (p.IsArray || p.IsPointer || p.IsByRef)
                                p = TypeManager.GetElementType (p);
                        
                        AccessLevel pAccess = TypeEffectiveAccessLevel (p);
                        AccessLevel mAccess = this.EffectiveAccessLevel &
                                GetAccessLevelFromModifiers (flags);
                        
                        // for every place from which we can access M, we must
                        // be able to access P as well. So, we want
                        // For every bit in M and P, M_i -> P_1 == true
                        // or, ~ (M -> P) == 0 <-> ~ ( ~M | P) == 0
                        
                        return ~ (~ mAccess | pAccess) == 0;
                }
                
                static DoubleHash dh = new DoubleHash (1000);

                Type DefineTypeAndParents (DeclSpace tc)
                {
                        DeclSpace container = tc.Parent;

                        if (container.TypeBuilder == null && container.Name != "")
                                DefineTypeAndParents (container);

                        return tc.DefineType ();
                }
                
                Type LookupInterfaceOrClass (string ns, string name, out bool error)
                {
                        DeclSpace parent;
                        Type t;
                        object r;
                        
                        error = false;

                        if (dh.Lookup (ns, name, out r))
                                return (Type) r;
                        else {
                                if (ns != ""){
                                        if (Namespace.IsNamespace (ns)){
                                                string fullname = (ns != "") ? ns + "." + name : name;
                                                t = TypeManager.LookupType (fullname);
                                        } else
                                                t = null;
                                } else
                                        t = TypeManager.LookupType (name);
                        }
                        
                        if (t != null) {
                                dh.Insert (ns, name, t);
                                return t;
                        }

                        //
                        // In case we are fed a composite name, normalize it.
                        //
                        int p = name.LastIndexOf ('.');
                        if (p != -1){
                                ns = MakeFQN (ns, name.Substring (0, p));
                                name = name.Substring (p+1);
                        }
                        
                        parent = RootContext.Tree.LookupByNamespace (ns, name);
                        if (parent == null) {
                                dh.Insert (ns, name, null);
                                return null;
                        }

                        t = DefineTypeAndParents (parent);
                        if (t == null){
                                error = true;
                                return null;
                        }
                        
                        dh.Insert (ns, name, t);
                        return t;
                }

                public static void Error_AmbiguousTypeReference (Location loc, string name, Type t1, Type t2)
                {
                        Report.Error (104, loc,
                                      String.Format ("`{0}' is an ambiguous reference ({1} or {2}) ", name,
                                                     t1.FullName, t2.FullName));
                }

                /// <summary>
                ///   GetType is used to resolve type names at the DeclSpace level.
                ///   Use this to lookup class/struct bases, interface bases or 
                ///   delegate type references
                /// </summary>
                ///
                /// <remarks>
                ///   Contrast this to LookupType which is used inside method bodies to 
                ///   lookup types that have already been defined.  GetType is used
                ///   during the tree resolution process and potentially define
                ///   recursively the type
                /// </remarks>
                public Type FindType (Location loc, string name)
                {
                        Type t;
                        bool error;

                        //
                        // For the case the type we are looking for is nested within this one
                        // or is in any base class
                        //
                        DeclSpace containing_ds = this;

                        while (containing_ds != null){
                                Type container_type = containing_ds.TypeBuilder;
                                Type current_type = container_type;

                                while (current_type != null && current_type != TypeManager.object_type) {
                                        string pre = current_type.FullName;

                                        t = LookupInterfaceOrClass (pre, name, out error);
                                        if (error)
                                                return null;
                                
                                        if ((t != null) && containing_ds.CheckAccessLevel (t))
                                                return t;

                                        current_type = current_type.BaseType;
                                }
                                containing_ds = containing_ds.Parent;
                        }

                        //
                        // Attempt to lookup the class on our namespace and all it's implicit parents
                        //
                        for (NamespaceEntry ns = NamespaceEntry; ns != null; ns = ns.ImplicitParent) {
                                t = LookupInterfaceOrClass (ns.FullName, name, out error);
                                if (error)
                                        return null;
                                
                                if (t != null) 
                                        return t;
                        }
                        
                        //
                        // Attempt to do a direct unqualified lookup
                        //
                        t = LookupInterfaceOrClass ("", name, out error);
                        if (error)
                                return null;
                        
                        if (t != null)
                                return t;
                        
                        //
                        // Attempt to lookup the class on any of the `using'
                        // namespaces
                        //

                        for (NamespaceEntry ns = NamespaceEntry; ns != null; ns = ns.Parent){

                                t = LookupInterfaceOrClass (ns.FullName, name, out error);
                                if (error)
                                        return null;

                                if (t != null)
                                        return t;

                                if (name.IndexOf ('.') > 0)
                                        continue;

                                string alias_value = ns.LookupAlias (name);
                                if (alias_value != null) {
                                        t = LookupInterfaceOrClass ("", alias_value, out error);
                                        if (error)
                                                return null;

                                        if (t != null)
                                                return t;
                                }

                                //
                                // Now check the using clause list
                                //
                                Type match = null;
                                foreach (Namespace using_ns in ns.GetUsingTable ()) {
                                        match = LookupInterfaceOrClass (using_ns.Name, name, out error);
                                        if (error)
                                                return null;

                                        if (match != null){
                                                if (t != null){
                                                        if (CheckAccessLevel (match)) {
                                                                Error_AmbiguousTypeReference (loc, name, t, match);
                                                                return null;
                                                        }
                                                        continue;
                                                }
                                                
                                                t = match;
                                        }
                                }
                                if (t != null)
                                        return t;
                        }

                        //Report.Error (246, Location, "Can not find type `"+name+"'");
                        return null;
                }

                /// <remarks>
                ///   This function is broken and not what you're looking for.  It should only
                ///   be used while the type is still being created since it doesn't use the cache
                ///   and relies on the filter doing the member name check.
                /// </remarks>
                public abstract MemberList FindMembers (MemberTypes mt, BindingFlags bf,
                                                        MemberFilter filter, object criteria);

                /// <remarks>
                ///   If we have a MemberCache, return it.  This property may return null if the
                ///   class doesn't have a member cache or while it's still being created.
                /// </remarks>
                public abstract MemberCache MemberCache {
                        get;
                }

                public override void ApplyAttributeBuilder (Attribute a, CustomAttributeBuilder cb)
                {
                        try {
                                TypeBuilder.SetCustomAttribute (cb);
                        } catch (System.ArgumentException e) {
                                Report.Warning (-21, a.Location,
                                                "The CharSet named property on StructLayout\n"+
                                                "\tdoes not work correctly on Microsoft.NET\n"+
                                                "\tYou might want to remove the CharSet declaration\n"+
                                                "\tor compile using the Mono runtime instead of the\n"+
                                                "\tMicrosoft .NET runtime\n"+
                                                "\tThe runtime gave the error: " + e);
                        }
                }

                /// <summary>
                /// Goes through class hierarchy and get value of first CLSCompliantAttribute that found.
                /// If no is attribute exists then return assembly CLSCompliantAttribute.
                /// </summary>
                public bool GetClsCompliantAttributeValue ()
                {
                        if ((caching_flags & Flags.HasCompliantAttribute_Undetected) == 0)
                                return (caching_flags & Flags.ClsCompliantAttributeTrue) != 0;

                        caching_flags &= ~Flags.HasCompliantAttribute_Undetected;

                        if (OptAttributes != null) {
                                EmitContext ec = new EmitContext (parent, this, Location,
                                                                  null, null, ModFlags, false);
                                Attribute cls_attribute = OptAttributes.GetClsCompliantAttribute (ec);
                                if (cls_attribute != null) {
                                        caching_flags |= Flags.HasClsCompliantAttribute;
                                        if (cls_attribute.GetClsCompliantAttributeValue (this)) {
                                                caching_flags |= Flags.ClsCompliantAttributeTrue;
                                                return true;
                                        }
                                        return false;
                                }
                        }

                        if (parent == null) {
                                if (CodeGen.Assembly.IsClsCompliant) {
                                        caching_flags |= Flags.ClsCompliantAttributeTrue;
                                        return true;
                                }
                                return false;
                        }

                        if (parent.GetClsCompliantAttributeValue ()) {
                                caching_flags |= Flags.ClsCompliantAttributeTrue;
                                return true;
                        }
                        return false;
                }


                // Tests container name for CLS-Compliant name (differing only in case)
                // Possible optimalization: search in same namespace only
                protected override bool IsIdentifierClsCompliant (DeclSpace ds)
                {
                        int l = Name.Length;

                        if (Namespace.LookupNamespace (NamespaceEntry.FullName, false) != null) {
                                // Seek through all imported types
                                foreach (string type_name in TypeManager.all_imported_types.Keys) 
                                {
                                        if (l != type_name.Length)
                                                continue;

                                        if (String.Compare (Name, type_name, true, CultureInfo.InvariantCulture) == 0 && 
                                                AttributeTester.IsClsCompliant (TypeManager.all_imported_types [type_name] as Type)) {
                                                Report.SymbolRelatedToPreviousError ((Type)TypeManager.all_imported_types [type_name]);
                                                return false;
                                }
                        }
                        }

                        // Seek through generated types
                        foreach (string name in RootContext.Tree.Decls.Keys) {
                                if (l != name.Length)
                                        continue;

                                if (String.Compare (Name, name, true, CultureInfo.InvariantCulture) == 0) { 

                                        if (Name == name)
                                                continue;
                                        
                                        DeclSpace found_ds = RootContext.Tree.Decls[name] as DeclSpace;
                                        if (found_ds.IsClsCompliaceRequired (found_ds.Parent)) {
                                                Report.SymbolRelatedToPreviousError (found_ds.Location, found_ds.GetSignatureForError ());
                                                return false;
                                        }
                                }
                        }

                        return true;
                }

                protected override string[] ValidAttributeTargets {
                        get {
                                return attribute_targets;
                        }
                }
        }

        /// <summary>
        ///   This is a readonly list of MemberInfo's.      
        /// </summary>
        public class MemberList : IList {
                public readonly IList List;
                int count;

                /// <summary>
                ///   Create a new MemberList from the given IList.
                /// </summary>
                public MemberList (IList list)
                {
                        if (list != null)
                                this.List = list;
                        else
                                this.List = new ArrayList ();
                        count = List.Count;
                }

                /// <summary>
                ///   Concatenate the ILists `first' and `second' to a new MemberList.
                /// </summary>
                public MemberList (IList first, IList second)
                {
                        ArrayList list = new ArrayList ();
                        list.AddRange (first);
                        list.AddRange (second);
                        count = list.Count;
                        List = list;
                }

                public static readonly MemberList Empty = new MemberList (new ArrayList ());

                /// <summary>
                ///   Cast the MemberList into a MemberInfo[] array.
                /// </summary>
                /// <remarks>
                ///   This is an expensive operation, only use it if it's really necessary.
                /// </remarks>
                public static explicit operator MemberInfo [] (MemberList list)
                {
                        Timer.StartTimer (TimerType.MiscTimer);
                        MemberInfo [] result = new MemberInfo [list.Count];
                        list.CopyTo (result, 0);
                        Timer.StopTimer (TimerType.MiscTimer);
                        return result;
                }

                // ICollection

                public int Count {
                        get {
                                return count;
                        }
                }

                public bool IsSynchronized {
                        get {
                                return List.IsSynchronized;
                        }
                }

                public object SyncRoot {
                        get {
                                return List.SyncRoot;
                        }
                }

                public void CopyTo (Array array, int index)
                {
                        List.CopyTo (array, index);
                }

                // IEnumerable

                public IEnumerator GetEnumerator ()
                {
                        return List.GetEnumerator ();
                }

                // IList

                public bool IsFixedSize {
                        get {
                                return true;
                        }
                }

                public bool IsReadOnly {
                        get {
                                return true;
                        }
                }

                object IList.this [int index] {
                        get {
                                return List [index];
                        }

                        set {
                                throw new NotSupportedException ();
                        }
                }

                // FIXME: try to find out whether we can avoid the cast in this indexer.
                public MemberInfo this [int index] {
                        get {
                                return (MemberInfo) List [index];
                        }
                }

                public int Add (object value)
                {
                        throw new NotSupportedException ();
                }

                public void Clear ()
                {
                        throw new NotSupportedException ();
                }

                public bool Contains (object value)
                {
                        return List.Contains (value);
                }

                public int IndexOf (object value)
                {
                        return List.IndexOf (value);
                }

                public void Insert (int index, object value)
                {
                        throw new NotSupportedException ();
                }

                public void Remove (object value)
                {
                        throw new NotSupportedException ();
                }

                public void RemoveAt (int index)
                {
                        throw new NotSupportedException ();
                }
        }

        /// <summary>
        ///   This interface is used to get all members of a class when creating the
        ///   member cache.  It must be implemented by all DeclSpace derivatives which
        ///   want to support the member cache and by TypeHandle to get caching of
        ///   non-dynamic types.
        /// </summary>
        public interface IMemberContainer {
                /// <summary>
                ///   The name of the IMemberContainer.  This is only used for
                ///   debugging purposes.
                /// </summary>
                string Name {
                        get;
                }

                /// <summary>
                ///   The type of this IMemberContainer.
                /// </summary>
                Type Type {
                        get;
                }

                /// <summary>
                ///   Returns the IMemberContainer of the parent class or null if this
                ///   is an interface or TypeManger.object_type.
                ///   This is used when creating the member cache for a class to get all
                ///   members from the parent class.
                /// </summary>
                IMemberContainer Parent {
                        get;
                }

                /// <summary>
                ///   Whether this is an interface.
                /// </summary>
                bool IsInterface {
                        get;
                }

                /// <summary>
                ///   Returns all members of this class with the corresponding MemberTypes
                ///   and BindingFlags.
                /// </summary>
                /// <remarks>
                ///   When implementing this method, make sure not to return any inherited
                ///   members and check the MemberTypes and BindingFlags properly.
                ///   Unfortunately, System.Reflection is lame and doesn't provide a way to
                ///   get the BindingFlags (static/non-static,public/non-public) in the
                ///   MemberInfo class, but the cache needs this information.  That's why
                ///   this method is called multiple times with different BindingFlags.
                /// </remarks>
                MemberList GetMembers (MemberTypes mt, BindingFlags bf);

                /// <summary>
                ///   Return the container's member cache.
                /// </summary>
                MemberCache MemberCache {
                        get;
                }
        }

        /// <summary>
        ///   The MemberCache is used by dynamic and non-dynamic types to speed up
        ///   member lookups.  It has a member name based hash table; it maps each member
        ///   name to a list of CacheEntry objects.  Each CacheEntry contains a MemberInfo
        ///   and the BindingFlags that were initially used to get it.  The cache contains
        ///   all members of the current class and all inherited members.  If this cache is
        ///   for an interface types, it also contains all inherited members.
        ///
        ///   There are two ways to get a MemberCache:
        ///   * if this is a dynamic type, lookup the corresponding DeclSpace and then
        ///     use the DeclSpace.MemberCache property.
        ///   * if this not a dynamic type, call TypeHandle.GetTypeHandle() to get a
        ///     TypeHandle instance for the type and then use TypeHandle.MemberCache.
        /// </summary>
        public class MemberCache {
                public readonly IMemberContainer Container;
                protected Hashtable member_hash;
                protected Hashtable method_hash;
                
                /// <summary>
                ///   Create a new MemberCache for the given IMemberContainer `container'.
                /// </summary>
                public MemberCache (IMemberContainer container)
                {
                        this.Container = container;

                        Timer.IncrementCounter (CounterType.MemberCache);
                        Timer.StartTimer (TimerType.CacheInit);

                        

                        // If we have a parent class (we have a parent class unless we're
                        // TypeManager.object_type), we deep-copy its MemberCache here.
                        if (Container.IsInterface) {
                                MemberCache parent;
                                
                                if (Container.Parent != null)
                                        parent = Container.Parent.MemberCache;
                                else
                                        parent = TypeHandle.ObjectType.MemberCache;
                                member_hash = SetupCacheForInterface (parent);
                        } else if (Container.Parent != null)
                                member_hash = SetupCache (Container.Parent.MemberCache);
                        else
                                member_hash = new Hashtable ();

                        // If this is neither a dynamic type nor an interface, create a special
                        // method cache with all declared and inherited methods.
                        Type type = container.Type;
                        if (!(type is TypeBuilder) && !type.IsInterface) {
                                method_hash = new Hashtable ();
                                AddMethods (type);
                        }

                        // Add all members from the current class.
                        AddMembers (Container);

                        Timer.StopTimer (TimerType.CacheInit);
                }

                /// <summary>
                ///   Bootstrap this member cache by doing a deep-copy of our parent.
                /// </summary>
                Hashtable SetupCache (MemberCache parent)
                {
                        Hashtable hash = new Hashtable ();

                        IDictionaryEnumerator it = parent.member_hash.GetEnumerator ();
                        while (it.MoveNext ()) {
                                hash [it.Key] = ((ArrayList) it.Value).Clone ();
                        }
                                
                        return hash;
                }


                /// <summary>
                ///   Add the contents of `new_hash' to `hash'.
                /// </summary>
                void AddHashtable (Hashtable hash, MemberCache cache)
                {
                        Hashtable new_hash = cache.member_hash;
                        IDictionaryEnumerator it = new_hash.GetEnumerator ();
                        while (it.MoveNext ()) {
                                ArrayList list = (ArrayList) hash [it.Key];
                                if (list == null)
                                        hash [it.Key] = list = new ArrayList ();

                                foreach (CacheEntry entry in (ArrayList) it.Value) {
                                        if (entry.Container != cache.Container)
                                                break;
                                        list.Add (entry);
                                }
                        }
                }

                /// <summary>
                ///   Bootstrap the member cache for an interface type.
                ///   Type.GetMembers() won't return any inherited members for interface types,
                ///   so we need to do this manually.  Interfaces also inherit from System.Object.
                /// </summary>
                Hashtable SetupCacheForInterface (MemberCache parent)
                {
                        Hashtable hash = SetupCache (parent);
                        TypeExpr [] ifaces = TypeManager.GetInterfaces (Container.Type);

                        foreach (TypeExpr iface in ifaces) {
                                Type itype = iface.Type;

                                IMemberContainer iface_container =
                                        TypeManager.LookupMemberContainer (itype);

                                MemberCache iface_cache = iface_container.MemberCache;

                                AddHashtable (hash, iface_cache);
                        }

                        return hash;
                }

                /// <summary>
                ///   Add all members from class `container' to the cache.
                /// </summary>
                void AddMembers (IMemberContainer container)
                {
                        // We need to call AddMembers() with a single member type at a time
                        // to get the member type part of CacheEntry.EntryType right.
                        AddMembers (MemberTypes.Constructor, container);
                        AddMembers (MemberTypes.Field, container);
                        AddMembers (MemberTypes.Method, container);
                        AddMembers (MemberTypes.Property, container);
                        AddMembers (MemberTypes.Event, container);
                        // Nested types are returned by both Static and Instance searches.
                        AddMembers (MemberTypes.NestedType,
                                    BindingFlags.Static | BindingFlags.Public, container);
                        AddMembers (MemberTypes.NestedType,
                                    BindingFlags.Static | BindingFlags.NonPublic, container);
                }

                void AddMembers (MemberTypes mt, IMemberContainer container)
                {
                        AddMembers (mt, BindingFlags.Static | BindingFlags.Public, container);
                        AddMembers (mt, BindingFlags.Static | BindingFlags.NonPublic, container);
                        AddMembers (mt, BindingFlags.Instance | BindingFlags.Public, container);
                        AddMembers (mt, BindingFlags.Instance | BindingFlags.NonPublic, container);
                }

                /// <summary>
                ///   Add all members from class `container' with the requested MemberTypes and
                ///   BindingFlags to the cache.  This method is called multiple times with different
                ///   MemberTypes and BindingFlags.
                /// </summary>
                void AddMembers (MemberTypes mt, BindingFlags bf, IMemberContainer container)
                {
                        MemberList members = container.GetMembers (mt, bf);

                        foreach (MemberInfo member in members) {
                                string name = member.Name;

                                // We use a name-based hash table of ArrayList's.
                                ArrayList list = (ArrayList) member_hash [name];
                                if (list == null) {
                                        list = new ArrayList ();
                                        member_hash.Add (name, list);
                                }

                                // When this method is called for the current class, the list will
                                // already contain all inherited members from our parent classes.
                                // We cannot add new members in front of the list since this'd be an
                                // expensive operation, that's why the list is sorted in reverse order
                                // (ie. members from the current class are coming last).
                                list.Add (new CacheEntry (container, member, mt, bf));
                        }
                }

                /// <summary>
                ///   Add all declared and inherited methods from class `type' to the method cache.
                /// </summary>
                void AddMethods (Type type)
                {
                        AddMethods (BindingFlags.Static | BindingFlags.Public |
                                    BindingFlags.FlattenHierarchy, type);
                        AddMethods (BindingFlags.Static | BindingFlags.NonPublic |
                                    BindingFlags.FlattenHierarchy, type);
                        AddMethods (BindingFlags.Instance | BindingFlags.Public, type);
                        AddMethods (BindingFlags.Instance | BindingFlags.NonPublic, type);
                }

                void AddMethods (BindingFlags bf, Type type)
                {
                        MemberInfo [] members = type.GetMethods (bf);

                        Array.Reverse (members);
                        
                        foreach (MethodBase member in members) {
                                string name = member.Name;

                                // Varargs methods aren't allowed in C# code.
                                if ((member.CallingConvention & CallingConventions.VarArgs) != 0)
                                        continue;

                                // We use a name-based hash table of ArrayList's.
                                ArrayList list = (ArrayList) method_hash [name];
                                if (list == null) {
                                        list = new ArrayList ();
                                        method_hash.Add (name, list);
                                }

                                // Unfortunately, the elements returned by Type.GetMethods() aren't
                                // sorted so we need to do this check for every member.
                                BindingFlags new_bf = bf;
                                if (member.DeclaringType == type)
                                        new_bf |= BindingFlags.DeclaredOnly;

                                list.Add (new CacheEntry (Container, member, MemberTypes.Method, new_bf));
                        }

                        
                }

                /// <summary>
                ///   Compute and return a appropriate `EntryType' magic number for the given
                ///   MemberTypes and BindingFlags.
                /// </summary>
                protected static EntryType GetEntryType (MemberTypes mt, BindingFlags bf)
                {
                        EntryType type = EntryType.None;

                        if ((mt & MemberTypes.Constructor) != 0)
                                type |= EntryType.Constructor;
                        if ((mt & MemberTypes.Event) != 0)
                                type |= EntryType.Event;
                        if ((mt & MemberTypes.Field) != 0)
                                type |= EntryType.Field;
                        if ((mt & MemberTypes.Method) != 0)
                                type |= EntryType.Method;
                        if ((mt & MemberTypes.Property) != 0)
                                type |= EntryType.Property;
                        // Nested types are returned by static and instance searches.
                        if ((mt & MemberTypes.NestedType) != 0)
                                type |= EntryType.NestedType | EntryType.Static | EntryType.Instance;

                        if ((bf & BindingFlags.Instance) != 0)
                                type |= EntryType.Instance;
                        if ((bf & BindingFlags.Static) != 0)
                                type |= EntryType.Static;
                        if ((bf & BindingFlags.Public) != 0)
                                type |= EntryType.Public;
                        if ((bf & BindingFlags.NonPublic) != 0)
                                type |= EntryType.NonPublic;
                        if ((bf & BindingFlags.DeclaredOnly) != 0)
                                type |= EntryType.Declared;

                        return type;
                }

                /// <summary>
                ///   The `MemberTypes' enumeration type is a [Flags] type which means that it may
                ///   denote multiple member types.  Returns true if the given flags value denotes a
                ///   single member types.
                /// </summary>
                public static bool IsSingleMemberType (MemberTypes mt)
                {
                        switch (mt) {
                        case MemberTypes.Constructor:
                        case MemberTypes.Event:
                        case MemberTypes.Field:
                        case MemberTypes.Method:
                        case MemberTypes.Property:
                        case MemberTypes.NestedType:
                                return true;

                        default:
                                return false;
                        }
                }

                /// <summary>
                ///   We encode the MemberTypes and BindingFlags of each members in a "magic"
                ///   number to speed up the searching process.
                /// </summary>
                [Flags]
                protected enum EntryType {
                        None            = 0x000,

                        Instance        = 0x001,
                        Static          = 0x002,
                        MaskStatic      = Instance|Static,

                        Public          = 0x004,
                        NonPublic       = 0x008,
                        MaskProtection  = Public|NonPublic,

                        Declared        = 0x010,

                        Constructor     = 0x020,
                        Event           = 0x040,
                        Field           = 0x080,
                        Method          = 0x100,
                        Property        = 0x200,
                        NestedType      = 0x400,

                        MaskType        = Constructor|Event|Field|Method|Property|NestedType
                }

                protected struct CacheEntry {
                        public readonly IMemberContainer Container;
                        public readonly EntryType EntryType;
                        public readonly MemberInfo Member;

                        public CacheEntry (IMemberContainer container, MemberInfo member,
                                           MemberTypes mt, BindingFlags bf)
                        {
                                this.Container = container;
                                this.Member = member;
                                this.EntryType = GetEntryType (mt, bf);
                        }
                }

                /// <summary>
                ///   This is called each time we're walking up one level in the class hierarchy
                ///   and checks whether we can abort the search since we've already found what
                ///   we were looking for.
                /// </summary>
                protected bool DoneSearching (ArrayList list)
                {
                        //
                        // We've found exactly one member in the current class and it's not
                        // a method or constructor.
                        //
                        if (list.Count == 1 && !(list [0] is MethodBase))
                                return true;

                        //
                        // Multiple properties: we query those just to find out the indexer
                        // name
                        //
                        if ((list.Count > 0) && (list [0] is PropertyInfo))
                                return true;

                        return false;
                }

                /// <summary>
                ///   Looks up members with name `name'.  If you provide an optional
                ///   filter function, it'll only be called with members matching the
                ///   requested member name.
                ///
                ///   This method will try to use the cache to do the lookup if possible.
                ///
                ///   Unlike other FindMembers implementations, this method will always
                ///   check all inherited members - even when called on an interface type.
                ///
                ///   If you know that you're only looking for methods, you should use
                ///   MemberTypes.Method alone since this speeds up the lookup a bit.
                ///   When doing a method-only search, it'll try to use a special method
                ///   cache (unless it's a dynamic type or an interface) and the returned
                ///   MemberInfo's will have the correct ReflectedType for inherited methods.
                ///   The lookup process will automatically restart itself in method-only
                ///   search mode if it discovers that it's about to return methods.
                /// </summary>
                ArrayList global = new ArrayList ();
                bool using_global = false;
                
                static MemberInfo [] emptyMemberInfo = new MemberInfo [0];
                
                public MemberInfo [] FindMembers (MemberTypes mt, BindingFlags bf, string name,
                                               MemberFilter filter, object criteria)
                {
                        if (using_global)
                                throw new Exception ();
                        
                        bool declared_only = (bf & BindingFlags.DeclaredOnly) != 0;
                        bool method_search = mt == MemberTypes.Method;
                        // If we have a method cache and we aren't already doing a method-only search,
                        // then we restart a method search if the first match is a method.
                        bool do_method_search = !method_search && (method_hash != null);

                        ArrayList applicable;

                        // If this is a method-only search, we try to use the method cache if
                        // possible; a lookup in the method cache will return a MemberInfo with
                        // the correct ReflectedType for inherited methods.
                        
                        if (method_search && (method_hash != null))
                                applicable = (ArrayList) method_hash [name];
                        else
                                applicable = (ArrayList) member_hash [name];

                        if (applicable == null)
                                return emptyMemberInfo;

                        //
                        // 32  slots gives 53 rss/54 size
                        // 2/4 slots gives 55 rss
                        //
                        // Strange: from 25,000 calls, only 1,800
                        // are above 2.  Why does this impact it?
                        //
                        global.Clear ();
                        using_global = true;

                        Timer.StartTimer (TimerType.CachedLookup);

                        EntryType type = GetEntryType (mt, bf);

                        IMemberContainer current = Container;


                        // `applicable' is a list of all members with the given member name `name'
                        // in the current class and all its parent classes.  The list is sorted in
                        // reverse order due to the way how the cache is initialy created (to speed
                        // things up, we're doing a deep-copy of our parent).

                        for (int i = applicable.Count-1; i >= 0; i--) {
                                CacheEntry entry = (CacheEntry) applicable [i];

                                // This happens each time we're walking one level up in the class
                                // hierarchy.  If we're doing a DeclaredOnly search, we must abort
                                // the first time this happens (this may already happen in the first
                                // iteration of this loop if there are no members with the name we're
                                // looking for in the current class).
                                if (entry.Container != current) {
                                        if (declared_only || DoneSearching (global))
                                                break;

                                        current = entry.Container;
                                }

                                // Is the member of the correct type ?
                                if ((entry.EntryType & type & EntryType.MaskType) == 0)
                                        continue;

                                // Is the member static/non-static ?
                                if ((entry.EntryType & type & EntryType.MaskStatic) == 0)
                                        continue;

                                // Apply the filter to it.
                                if (filter (entry.Member, criteria)) {
                                        if ((entry.EntryType & EntryType.MaskType) != EntryType.Method)
                                                do_method_search = false;
                                        global.Add (entry.Member);
                                }
                        }

                        Timer.StopTimer (TimerType.CachedLookup);

                        // If we have a method cache and we aren't already doing a method-only
                        // search, we restart in method-only search mode if the first match is
                        // a method.  This ensures that we return a MemberInfo with the correct
                        // ReflectedType for inherited methods.
                        if (do_method_search && (global.Count > 0)){
                                using_global = false;

                                return FindMembers (MemberTypes.Method, bf, name, filter, criteria);
                        }

                        using_global = false;
                        MemberInfo [] copy = new MemberInfo [global.Count];
                        global.CopyTo (copy);
                        return copy;
                }
                
                //
                // This finds the method or property for us to override. invocationType is the type where
                // the override is going to be declared, name is the name of the method/property, and
                // paramTypes is the parameters, if any to the method or property
                //
                // Because the MemberCache holds members from this class and all the base classes,
                // we can avoid tons of reflection stuff.
                //
                public MemberInfo FindMemberToOverride (Type invocationType, string name, Type [] paramTypes, bool is_property)
                {
                        ArrayList applicable;
                        if (method_hash != null && !is_property)
                                applicable = (ArrayList) method_hash [name];
                        else
                                applicable = (ArrayList) member_hash [name];
                        
                        if (applicable == null)
                                return null;
                        //
                        // Walk the chain of methods, starting from the top.
                        //
                        for (int i = applicable.Count - 1; i >= 0; i--) {
                                CacheEntry entry = (CacheEntry) applicable [i];
                                
                                if ((entry.EntryType & (is_property ? (EntryType.Property | EntryType.Field) : EntryType.Method)) == 0)
                                        continue;

                                PropertyInfo pi = null;
                                MethodInfo mi = null;
                                FieldInfo fi = null;
                                Type [] cmpAttrs = null;
                                
                                if (is_property) {
                                        if ((entry.EntryType & EntryType.Field) != 0) {
                                                fi = (FieldInfo)entry.Member;

                                                // TODO: For this case we ignore member type
                                                //fb = TypeManager.GetField (fi);
                                                //cmpAttrs = new Type[] { fb.MemberType };
                                        } else {
                                                pi = (PropertyInfo) entry.Member;
                                                cmpAttrs = TypeManager.GetArgumentTypes (pi);
                                        }
                                } else {
                                        mi = (MethodInfo) entry.Member;
                                        cmpAttrs = TypeManager.GetArgumentTypes (mi);
                                }

                                if (fi != null) {
                                        // TODO: Almost duplicate !
                                        // Check visibility
                                        switch (fi.Attributes & FieldAttributes.FieldAccessMask) {
                                                case FieldAttributes.Private:
                                                        //
                                                        // A private method is Ok if we are a nested subtype.
                                                        // The spec actually is not very clear about this, see bug 52458.
                                                        //
                                                        if (invocationType != entry.Container.Type &
                                                                TypeManager.IsNestedChildOf (invocationType, entry.Container.Type))
                                                                continue;

                                                        break;
                                                case FieldAttributes.FamANDAssem:
                                                case FieldAttributes.Assembly:
                                                        //
                                                        // Check for assembly methods
                                                        //
                                                        if (mi.DeclaringType.Assembly != CodeGen.Assembly.Builder)
                                                                continue;
                                                        break;
                                        }
                                        return entry.Member;
                                }

                                //
                                // Check the arguments
                                //
                                if (cmpAttrs.Length != paramTypes.Length)
                                        continue;
        
                                for (int j = cmpAttrs.Length - 1; j >= 0; j --)
                                        if (paramTypes [j] != cmpAttrs [j])
                                                goto next;
                                
                                //
                                // get one of the methods because this has the visibility info.
                                //
                                if (is_property) {
                                        mi = pi.GetGetMethod (true);
                                        if (mi == null)
                                                mi = pi.GetSetMethod (true);
                                }
                                
                                //
                                // Check visibility
                                //
                                switch (mi.Attributes & MethodAttributes.MemberAccessMask) {
                                case MethodAttributes.Private:
                                        //
                                        // A private method is Ok if we are a nested subtype.
                                        // The spec actually is not very clear about this, see bug 52458.
                                        //
                                        if (invocationType == entry.Container.Type ||
                                            TypeManager.IsNestedChildOf (invocationType, entry.Container.Type))
                                                return entry.Member;
                                        
                                        break;
                                case MethodAttributes.FamANDAssem:
                                case MethodAttributes.Assembly:
                                        //
                                        // Check for assembly methods
                                        //
                                        if (mi.DeclaringType.Assembly == CodeGen.Assembly.Builder)
                                                return entry.Member;
                                        
                                        break;
                                default:
                                        //
                                        // A protected method is ok, because we are overriding.
                                        // public is always ok.
                                        //
                                        return entry.Member;
                                }
                        next:
                                ;
                        }
                        
                        return null;
                }
        }
}